1. Field of the Invention
The present invention relates to a process for fabricating a color filter, and more particularly to a process for fabricating a color element of the color filter.
2. Description of the Related Art
Color filters (CF) have been popularly employed in video products, such as color liquid crystal displays, charge coupled devices, and scanners, to obtain ample color information. With regard to a liquid crystal display (LCD) with light, thin, power-saving and full color features, a color filter with three primary colors including red (R), green (G) and blue (B) elements is required for dividing a pixel into R, G and B subpixels. The three primary colors are blended with each other in proportion to create various colors, thus enabling the LCD to display bright, realistic and vivid pictures, enhancing functionality of the LCD.
In a conventional CF process, thin-film color layers including R, G and B layers are successively coated on a glass substrate to serve as R, G and B elements, which must then be precisely aligned to pixel areas on the TFT array substrate. In view of manufacturing costs and quality requirements, dyeing, pigment dispersion, printing and electroplating are commonly used to form the R, G and B elements of the color filter. Pigment dispersion which provides the color filter with high precision and superior light-resistance and heat-resistance has become a major process in recent TFT-type color filter technologies.
The pigment dispersion method applied in the conventional color filter process includes the following steps. A black photosensitive resin material is spin-coated on a glass substrate, and then subjected to a photolithography process, that is, exposed to light, developed and baked, to form a black matrix (BM) having an array of openings for color elements. Then, red, green, and blue resin materials are respectively spin-coated and subjected to the photolithography process to form three different color elements, such that the red, green, and blue elements fill the opening of the black matrix in a desired arrangement. As mentioned above, the pigment dispersion method includes resin coating, exposure, and development procedures. Thus, any inaccuracy in these processes would cause the color elements have inferior color uniformity and resolution, and inaccurate alignment.
In addition, the photolithography process is a wet etching process, which defines the pattern by means of the chemical dissolution between the chemical solution and the resin material. Therefore, the development effect is easily varied by the concentration of the chemical solution, which in turn affects pattern uniformity and film flatness. In addition, equipment cost for photolithography is very expensive and the process time is long, hence it does not meet requirements for mass production. Further, the use of developer requires subsequent waste treatment. Additionally, solvent evaporation is detrimental to environment and the humans alike.